Changing Slider Mounting Point Birdcages

[DirtRacer9x]

What happens when you move the mounting point further away from centerline of axle vs closer to it maintaining the same ride height? Thanks

[keeks]

I'm not sure what you mean by slider. Do you mean indexing the top bar on the cage?

[DirtRacer9x]

I'm not sure what you mean by slider. Do you mean indexing the top bar on the cage?

On the birdcages where you can raise or lower the mount on birdcage for the slider to clarify.

[Brian Gray]

A number of things happen but I'll Focus on the 3 I feel are most important. First probly most important if your talking about the top link increasing the distance will lower the rate of indexing. Secondly it will change roll steer. 3 you increase the ratio of leverage which increases rotation control but lowers the loaded force during indexing.

[TALON75]

A slider is a LR spring assembly without a shock, commonly found on modifieds that can't have more than one shock per wheel, some limited LM'S also have a similar rule. By moving it down you will achieve more indexing into the spring which "should" also give more drive.

[DirtRacer9x]

So lower on the birdcage will create more indexing into the spring? Will it affect the way the car gets onto the bars at all? Meaning does it think a heavier spring is on the birdcage he higher or lower it goes? Thanks!

[TALON75]

I personally don't think there is much there, we move ours to achieve more drop sometimes and it doesn't seem to have much effect elsewhere. It will slow the reaction down a little, but not sure if it thinks it has a heavier spring or not.

[TheJet-09]

Out of curiosity, are you thinking/talking about lowering the coil-over assembly's upper mounting point as well, or just increasing its overall length when lowering the bottom?

[keeks]

A slider is a LR spring assembly without a shock, commonly found on modifieds that can't have more than one shock per wheel, some limited LM'S also have a similar rule. By moving it down you will achieve more indexing into the spring which "should" also give more drive.

OK. Now I understand. Thanks.

[DirtRacer9x]

The upper is fixed on this chassis as far as moving up and down. It can only tilt in or out from 0 degrees to 25 degrees inward. But the birdcage has multiple mounting locations up or down. Right now I just picked the center holes but it has about 6" of adjustment from mounting lower part of slider even with axle tube to dropping it down 6" below axle centerline. So right now I'm sitting at about 3" below centerline. I don't see how it would affect indexing overall though. I can only see a change at a leverage point perspective.

[Matt49]

Moving it further from the center changes the motion ratio. So with the same amount of birdcage indexing, you're going to have increased motion of the mount which will in theory give the car a little more drive.

Most late models have their lower shock mounts from 5-7 inches below the centerline of the axle.

[DirtRacer9x]

So it will create more drive lower down? So possibly this can be an adjustment for when track slicks off?

[Bcollins82]

So it will create more drive lower down? So possibly this can be an adjustment for when track slicks off?

Yes, it will drive harder, but not a good adjustment unless you like resetting wedge at the track after you change it, and you can do basically the same thing by lowering your upper on the birdcage. There are better adjustments to utilize at the track than changing your lower shock mounting position. Also, if you go too far, and your spring indexes upward faster than your axle drops (this can happen at the end of your downward travel) you can lose forward drive.

[JTSjet]

i've messed around with this a fair amount this season. this is what i learned so far:

- watch your scrub line. if you get the lower shock mount below the wheel rim and you get a LR flat.....bent birdcage. murhphy's law

- increasing the motion ratio does seem to help drive HOWEVER just use caution when making an adjustment that will increase birdcage indexing. it exaggerates the change you made

- in some cases you are reducing shock angle (increasing effective spring rate) which may be counter productive.

[DirtRacer9x]

i've messed around with this a fair amount this season. this is what i learned so far:- watch your scrub line. if you get the lower shock mount below the wheel rim and you get a LR flat.....bent birdcage. murhphy's law- increasing the motion ratio does seem to help drive HOWEVER just use caution when making an adjustment that will increase birdcage indexing. it exaggerates the change you made- in some cases you are reducing shock angle (increasing effective spring rate) which may be counter productive.

Best answer so far and actually tried it. Thank you. Any other input you have would be great! Also find any sweet spot and just leave it? Shock in front higher or lower than the slider behind? Thanks!